Webmail: Authentication Bypass by Spoofing
CVE-2026-62644 is a critical-severity authentication bypass by spoofing vulnerability in Webmail from Roundcube, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 1.6.17, 1.7.2 as the first without the flaw, so updating Webmail to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.26% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Webmail to 1.6.17 or 1.7.2, whichever matches your release line, or a later version.
- Read the advisory on roundcube.net for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Roundcube | Webmail | 1.6.0 up to, but not including, 1.6.17; 1.7.0 up to, but not including, 1.7.2 | 1.6.17, 1.7.2 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.4 | Medium | CNA (mitre.org) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
In Roundcube Webmail before 1.6.17 and 1.7.x before 1.7.2, the password plugin of the Roundcube Webmail was subject to username spoofing via session data, which could lead to account takeover.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass by Spoofing
This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
More Authentication Bypass by Spoofing vulnerabilities (CWE-290)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/roundcube/roundcubemail/commit/5cdc6a48b40beabff7f0bf5d9035f4491e877e4c
- github.com/roundcube/roundcubemail/commit/7414fef51cd2407d39faab99680763f10ed5231d
- github.com/roundcube/roundcubemail/commit/83150ce04d689a70f92d511bcae40adba8d55476
- github.com/roundcube/roundcubemail/commit/9a96c20d8c7c9135876b68bebd6960af3ee60923
- github.com/roundcube/roundcubemail/releases/tag/1.6.17Release Notes
- github.com/roundcube/roundcubemail/releases/tag/1.7.2Release Notes
Other vulnerabilities in Webmail
- 8.1 High severity
- 7.2 High severity
- 8.3 High severity
- 8.1 High severity
- 7.1 High severity
- 8.5 High severity
Recent Authentication Bypass by Spoofing vulnerabilities
- 7.5 High severity
- 9.1 Critical severity
- 8.1 High severity
- 9.1 Critical severity
- 7.3 High severity
- 8.2 High severity
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